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AGPN40 KWNM 232035
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
135 PM PDT Fri Jun 23 2017

.FORECAST DISCUSSION...Major features/winds/seas/significant
.weather for the North Pacific N of 30N and E of 150W.

Grids: 12z GFS 10m winds, 12z WW3 throughout. Brief discussion
with some modifications mentioned below.

ASCAT-B overpass at 18z provided sea truth to the ongoing forecast,
with all wind retrievals 30 kt or less. Strongest gradient winds
in the 25 to 30 kt range were located in the waters adjacent to
Point St. George and Cape Blanco, extending westward 250 nm
covering the waters of inner zones 815 and 820, and the outer
zones 915 and 920. Weakening trend will continue this evening and
overnight, with winds diminishing below 25 kt by late tomorrow
morning.

Over the weekend fairly quiet conditions / weak associated
gradients / flat seas forecast as weak coastal trough shifts to
the coastal Pacific NW, and high pressure ridging noses into the
central waters. Late in the forecast period, Tue into Wed night,
all global models signaling another round of strong prevailing
northerlies building off the northern CA and southwest OR coasts
between strengthening coastal low pressure trough and building E
Pacific high pressure. As of now strength of gradient suggests
possible gales, but only marginal confidence in timing and
coverage this far out in the forecast. Will limit winds in the
extended period to 30 kt with the afternoon issuance, and allow
future shifts and model runs to dictate if or when warning
headlines are needed.

Seas: little differences noted when comparing the 12z WAM and
WW3, and with deference to the GFS in the wind grids, have no
issues using the WW3 throughout the forecast period.

Extratropical Storm Surge Guidance: n/a.


.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
     None.

$$

.Forecaster Collins. Ocean Prediction Center.


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